[libvirt] [PATCH 3/7] qemu: Remove possibility of NULL dereference

[John Ferlan]

If qemubinCaps is NULL, then calling virQEMUCapsGetMachineTypesCaps and
dereferencing to get the nmachineTypes will cause a core. Rework the code
slightly to avoid the issue and return immediately if !qemubinCaps or
!nmachineTypes

Signed-off-by: John Ferlan <jferlan at redhat.com>
---
 src/qemu/qemu_capabilities.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index da8f3d1..ee3e50f 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -2405,10 +2405,13 @@ int virQEMUCapsGetMachineTypesCaps(virQEMUCapsPtr qemuCaps,
     size_t i;
 
     *machines = NULL;
+    *nmachines = 0;
+
+    if (!qemuCaps || !qemuCaps->nmachineTypes)
+        return 0;
     *nmachines = qemuCaps->nmachineTypes;
 
-    if (*nmachines &&
-        VIR_ALLOC_N(*machines, qemuCaps->nmachineTypes) < 0)
+    if (VIR_ALLOC_N(*machines, qemuCaps->nmachineTypes) < 0)
         goto error;
 
     for (i = 0; i < qemuCaps->nmachineTypes; i++) {
-- 
2.7.4